| abstract |
The present invention provides a method for extracting struvite, in particular a method for extracting struvite from seawater, a concentrated salt solution or brine. The method comprises firstly subjecting seawater, a concentrated salt solution or brine to sand filtration to remove impurity particles, adding a corresponding amount of NH4HCO3 and H3PO4 according to the concentration of Mg2+ in seawater, the concentrated salt solution or brine, sufficiently stirring and mixing NH4HCO3 and H3PO4 with seawater, the concentrated salt solution or brine for a reaction; dropwise adding an electromagnetic ionic liquid, controlling the period of dropwise addition to be 30-50 min, controlling the pH value of the reaction liquid within a range of 7.5-8.5 at the same time, and performing a sufficient reaction to form a white precipitate; and finally, separating the white precipitate from the liquid by means of solid-liquid separation, performing centrifugation and spin-drying, and packing the resultant into a bag, so as to obtain struvite. The struvite produced by the method has higher purity and fertilizer efficiency than natural struvite, and also contains potassium, calcium, sulfur, chlorine and other elements required for crop growth as well as a large amount of zinc, manganese, iron, copper, selenium and other trace elements, being more suitable for crop growth. |